L4D2 have the story in the wiki pages. And I read the comics long time ago.The L4D1 story here means what happen when these characters come from this campaign to the next campaign. Example is when these characters get on the Helicopter in No Mercy campaign, what campaign is the next to go? It's the Crash Course Campaign. But how about Dead Air? Start in The Greenhouse, Why?? Death Toll, Blood Harvest,...

Wiki is nothing more than Fan-fiction. In that you can makeup any story that you wish as to how the survivors got to the Starting location of Blood Harvest, Death Toll and Dead Air..

Valve didn't have a real order for the campaigns until after Sacrifice was released. Then some updates later, Valve put the campaigns in story order in L4D1 on the selection list. And Ironically (not really), they did that after a thread discussing possible orders of the campaigns was deduced on the forums, by us gamers.

Although, it wasn't that hard to figure out an order based on the DLC's (the only real story arcs the game received.) of Crash Course, Sacrifice and the Comic.

Crash Course's order is given by character banter between Zoey and Frances. Just bring the two characters to the dead helicopter pilot and the character banter shows that this campaign is after No Mercy. We all know that the start is No Mercy, thanks to the Intro Video. And then the Comic used Blood Harvest as it's starting point. The missing ones being Dead Air and Death Toll, which both came with the game initially, were just logically placed in between by fans, where they made the most sense.

So, that's would be the explanation of why Dead Air starts in a Greenhouse... And why no Story is given to why they had to leave the C-130 behind, or how they got off the thing. And ditto for the Boat.

It's likely that Valve planned to fill in the gaps with more DLC's but instead they decided to dump L4D and focus on L4D2...

Not as much story and dialogue exchange as in L4D2 (which I guess should be expected - the first game was pretty experimental and they had more room to stretch and add with L4D2), but there is definitely a bit of a story and they did what they could to add on to it/cap it off with the DLC campaigns like The Sacrafice.

There's a definite progressing plot in both games but it's designed so that any campaign can be played as it's own complete piece. It's more arcade-focus with supplemental story bits for fun.

Atleast theres room to put anything...makes me think of that single player counter strike. For the same lack of charachter depth I dont ever think of L4D2 as what came after a decision to dump L4D1. One campaign can be arcade fun or expert realism adventure/nightmare lol.